Last year twitter stopped delivery of outbound SMS over its UK number because of its huge cost. This means that if you do not live in US, Canada or India, you are not going to get twitter updates  Twitter admin managed to reduce their cost of operations and actually get little bit of money in these countries by establishing a reciprocal relationship with local mobile operators. I dont know why, but I am sure that no Pakistani cellular operator will ever make such relationship with twitter :S (any operator rep. reading this??). So, the only solution left is to use m.twitter.com or iPhone to get updated on your cellular device.

I was planning to make an application for Pakistani users to use twitter via local number and get updated via local SMS. Today, Yaser invited me to the iSMS twitter service for Pakistan. This simple application allows you to change your status using a local number making it cheaper. 

You can see this message in your iSMS settings page. Click on the Integrate your account link

Enter your twitter username and password

Updated status on twitter

Enjoy tweeting in Pakistan